A common type of printer architecture is a carriage printer, where a printhead array of marking elements is somewhat smaller than an extent of a region of interest for printing on a recording medium and a printhead is mounted on a carriage. In a carriage printer, the recording medium is advanced a given distance along a media advance direction and then stopped. While the recording medium is stopped, the printhead is moved by the carriage in a carriage scan direction that is substantially perpendicular to the media advance direction as marks are controllably made by marking elements. After the printhead has printed a swath of an image while traversing the recording medium, the recording medium is advanced, the carriage direction of motion is reversed, and the image is formed swath by swath.
One example of a carriage printer is an inkjet printer. An inkjet printing system typically includes one or more printheads and their corresponding ink supplies. Each printhead includes an ink inlet that is connected to its ink supply and an array of drop ejectors, each ejector consisting of an ink pressurization chamber, an ejecting actuator and a nozzle through which droplets of ink are ejected. The ejecting actuator can be one of various types, including a heater that vaporizes some of the ink in a pressurization chamber in order to propel a droplet out of an orifice, or a piezoelectric device which changes the wall geometry of the chamber in order to generate a pressure wave that ejects a droplet. The droplets are typically directed toward paper or other recording medium in order to produce an image according to image data that is converted into electronic firing pulses for the drop ejectors as the printhead is moved relative to the recording medium.
Faster printing throughput can be achieved in the carriage printer by printing at a faster carriage speed. However, the distance (d) required to accelerate from a stopped position to a constant velocity vc (and similarly to decelerate to a stopped position) is given by d=vc2/2a, where (a) is the acceleration. Therefore, as the carriage velocity is increased, it is desirable to increase the acceleration so that the width of the acceleration region beyond the print region doesn't increase to unacceptable levels, requiring that the printer be significantly wider than the print media. Such acceleration and deceleration can cause significant forces, particularly for carriages having a large mass, which can tend to cause the carriage printer to shake.
Many inkjet printers carry their ink supplies on the carriage. It is desirable for the ink supplies of the various colors (typically cyan, magenta, yellow and black, and sometimes other inks as well) be large enough for printing of at least several hundred pages, so that the user is not required to replace ink tanks too frequently. However, the more ink that is carried by the carriage, the higher the carriage mass is, and consequently the higher the forces are that result when the carriage accelerates and decelerates.
Different users of printers have different work environments that are not always predictable. Many users operate their printers on a sturdy work surface such as a massive desk. Others operate their printers on a surface, such as a file cabinet, that is not generally intended as a support surface for a printer. Still other users operate their printer on whatever type of table they happen to have. For example, some users operate their printers on lightweight card tables having foldable legs. A relatively flimsy work surface such as this can be more dramatically impacted by carriage forces than a sturdy support structure. The resulting shaking of the work surface can be noisy and annoying, and can result in damage. For example, if the user has a laptop computer, a carriage printer, some documents and a glass of water on a card table that is caused to shake by carriage motion, water could slosh out of the glass and onto the documents or laptop computer and damage them.
Printer manufacturers are thus typically constrained by the unpredictability of the user's environment and make trade-offs between slowing down printing throughput by reducing carriage acceleration and limiting the amount of ink that is moved by the carriage. What is needed is a carriage printer and a method of operating the printer that is able to monitor its motion within the user's environment and adjust its carriage motion control accordingly.